1. Field of the Invention
The present invention relates to an electronic endoscope applicable for performing treatment using a treatment tool.
2. Description of the Related Art
In recent years, electronic endoscopes whereupon a solid-state image-capturing device is mounted have been widely used in medical fields and so forth. As a first preceding example of an electronic endoscope, for example, Japanese Unexamined Patent Application Publication No. 2003-230533 discloses an endoscope having a lateral view or a rear perspective as the field of vision.
Also, as a second preceding example of an electronic endoscope, for example, Japanese Unexamined Patent Application Publication No. 2004-72526 discloses an electronic endoscope having a channel capable of inserting the treatment tool through, and having lateral view or a rear perspective as the field of vision.
In the above second preceding example, a wedge-shaped lens is used wherein the field of view angle on the upper side is thicker than the field of view angle on the lower side, as a lens on the foremost tip portion of the objective optical system.
Note that with an endoscope with a lateral view or a rear perspective as the field of vision having an erecting block which changes the protruding direction of the treatment tool, an objective optical system and erecting block are adjacently disposed in the left and right directions perpendicular to the lengthwise direction on the tip portion of the insertion portion. Also, with the erecting block disposed in the vicinity of the channel exit, if the tip side of the treatment tool is protruded from the channel exit in the state of the protruding direction being restricted, the tip side of the protruded treatment tool is to be captured in the field of view angle of the objective optical system.
In this case, if the field of view angle of the objective optical system has the base end side of the insertion portion at the upper direction of the field of vision and the tip side of the insertion portion at the lower direction of the field of vision, the objective optical system and erecting block are disposed on the tip portion of the insertion portion so that the tip side of the protruded treatment tool enters in the field of vision on the upper side. Also, in a case of an optical image, which is formed by the objective optical system, being photoelectrically converted by the image-capturing device and displayed on a display device as the endoscope image, relating to the field of vision direction in the center of the objective optical system, this image is displayed so that the base side of the insertion portion is displayed in the upper direction of the observation image and the tip side of the insertion portion is displayed in the lower direction of the observation image. In the case of performing treatment such as ERCP (Endoscopic Retrograde Cholangiopancreatography) for example, using an endoscope with a lateral view or rear perspective having an erecting block which changes the protruding direction of the treatment tool, the erecting block is operated to change the protruding direction of the treatment tool, and a procedure is performed to insert a catheter from the duodenal papilla to the bile duct (or pancreatic duct). When performing such treatment, the treatment tool having changed the protruding direction by the erecting block is set for the tip thereof to be displayed on the upper half of the observation image which the surgeon observes.